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<div class="titlepage"><div><div><h4 class="title">
<a name="asio.reference.read.overload11"></a><a class="link" href="overload11.html" title="read (11 of 12 overloads)">read (11 of 12 overloads)</a>
</h4></div></div></div>
<p>
          Attempt to read a certain amount of data from a stream before returning.
        </p>
<pre class="programlisting">template&lt;
    typename <a class="link" href="../SyncReadStream.html" title="Buffer-oriented synchronous read stream requirements">SyncReadStream</a>,
    typename Allocator,
    typename <a class="link" href="../CompletionCondition.html" title="Completion condition requirements">CompletionCondition</a>&gt;
std::size_t read(
    SyncReadStream &amp; s,
    basic_streambuf&lt; Allocator &gt; &amp; b,
    CompletionCondition completion_condition);
</pre>
<p>
          This function is used to read a certain number of bytes of data from a
          stream. The call will block until one of the following conditions is true:
        </p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
              The supplied buffer is full (that is, it has reached maximum size).
            </li>
<li class="listitem">
              The completion_condition function object returns 0.
            </li>
</ul></div>
<p>
          This operation is implemented in terms of zero or more calls to the stream's
          read_some function.
        </p>
<h6>
<a name="asio.reference.read.overload11.h0"></a>
          <span><a name="asio.reference.read.overload11.parameters"></a></span><a class="link" href="overload11.html#asio.reference.read.overload11.parameters">Parameters</a>
        </h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl>
<dt><span class="term">s</span></dt>
<dd><p>
                The stream from which the data is to be read. The type must support
                the SyncReadStream concept.
              </p></dd>
<dt><span class="term">b</span></dt>
<dd><p>
                The <a class="link" href="../basic_streambuf.html" title="basic_streambuf"><code class="computeroutput">basic_streambuf</code></a>
                object into which the data will be read.
              </p></dd>
<dt><span class="term">completion_condition</span></dt>
<dd>
<p>
                The function object to be called to determine whether the read operation
                is complete. The signature of the function object must be:
</p>
<pre class="programlisting">std::size_t completion_condition(
  // Result of latest read_some operation.
  const asio::error_code&amp; error,

  // Number of bytes transferred so far.
  std::size_t bytes_transferred
);
</pre>
<p>
                A return value of 0 indicates that the read operation is complete.
                A non-zero return value indicates the maximum number of bytes to
                be read on the next call to the stream's read_some function.
              </p>
</dd>
</dl>
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<h6>
<a name="asio.reference.read.overload11.h1"></a>
          <span><a name="asio.reference.read.overload11.return_value"></a></span><a class="link" href="overload11.html#asio.reference.read.overload11.return_value">Return
          Value</a>
        </h6>
<p>
          The number of bytes transferred.
        </p>
<h6>
<a name="asio.reference.read.overload11.h2"></a>
          <span><a name="asio.reference.read.overload11.exceptions"></a></span><a class="link" href="overload11.html#asio.reference.read.overload11.exceptions">Exceptions</a>
        </h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl>
<dt><span class="term">asio::system_error</span></dt>
<dd><p>
                Thrown on failure.
              </p></dd>
</dl>
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<td align="right"><div class="copyright-footer">Copyright &#169; 2003-2018 Christopher M. Kohlhoff<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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